Table 4.
Regression parameters for the relationships between nitrous oxide (N2O) emission and TNU, NRE and net N balance when N fertilizer sources involved urea, ESN, and stabilized N (SUPERU, AgrotainPlus).
| N Source | TNU | NRE | NNB(TNU) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| N | Reg. model | R2 | P < F | N | Reg. model | R2 | P < F | N | Reg. model | R2 | P < F | |
| Urea | 32 | y = 0.001x+1.63 | 0.00 | 0.81 | 20 | y = 0.012x+0.54 | 0.14 | 0.10 | 32 | y = −0.007x+1.90 | 0.11 | 0.06 |
| ESN | 30 | y = −0.002x+2.62 | 0.00 | 0.87 | 18 | y = 0.029x−0.11 | 0.21 | 0.06 | 30 | y = −0.016x+2.26 | 0.10 | 0.08 |
| Stabilized N | 23 | y = 0.005x−0.02 | 0.03 | 0.40 | 23 | y = 0.012x+0.28 | 0.07 | 0.62 | 23 | y = −0.006x+0.94 | 0.15 | 0.07 |
| Across N sources | 61 | y = 0.001x+1.56 | 0.00 | 0.84 | 61 | y = 0.021x+0.12 | 0.14 | 0.01 | 85 | y = −0.011x+1.79 | 0.09 | 0.01 |
ESN, Environmentally smart nitrogen (polymer-coated urea; 44-0-0); stabilized N, nitrification+urease inhibitors: Agrotain with urea (46-0-0), AgrotainPlus with urea ammonium-nitrate (28-0-0), superU (urea 46-0-0). N, number of observations; TNU, total nitrogen uptake; NRE, N recovery efficiency; NNB(TNU), net nitrogen balance.